title: Effects of beam collimation on image quality.
abstract: OBJECTIVE
  The purpose of this study was to determine the effect of three film-speed/collimator combinations on image quality, based on reviewer preference and diagnostic quality, based on caries detection.
  
  
  METHODS
  Two hundred sixteen proximal surfaces were evaluated for the presence and severity of carious lesions on bitewing-simulated projections using D-speed film/circular, E-speed film/rectangular, and E-speed film/circular collimation. Matched films by model type were ranked, based on reviewer preference. Preference data were analyzed using Friedman's test, while the caries detection data were analyzed using a 3 x 3 x 3 x 6 ANOVA model and the kappa statistic. Variability components of the ANOVA were used to determine inter- and intra-rater reliability.
  
  
  RESULTS
  Inter- and intra-rater reliability were 90.9 and 98.7%, respectively. Each of the film-speed/collimator combinations had average preference rankings that were significantly different from one another for each criteria (p < 0.001), with E-speed film/rectangular collimation consistently ranking highest and E-speed film/circular collimation consistently ranking lowest. There was excellent agreement in caries detection among the three film-speed/collimator combinations (kw = 0.92, kw = 0.94).
  
  
  CONCLUSIONS
  Results from the subjective comparison indicated that E-speed film with rectangular collimation ranked highest for film resolution, overall appearance, and choice for caries diagnosis, while E-speed film with circular collimation ranked lowest. Caries diagnosis was comparable among the three film-speed/collimator combinations.
authors.affiliation: Department of Biostatistics, School of Public Health, University of North Carolina-Chapel Hill, USA.
authors.forename: C A
authors.initials: CA
authors.lastname: Peterson
authors.forename: S M
authors.initials: SM
authors.lastname: Mauriello
authors.forename: V P
authors.initials: VP
authors.lastname: Overman
authors.forename: E
authors.initials: E
authors.lastname: Platin
authors.forename: C M
authors.initials: CM
authors.lastname: Tangen
mesh_terms: D000704:Analysis of Variance; D003731:Dental Caries / Q000000981:diagnostic imaging; D005069:Evaluation Studies as Topic; D006801:Humans; D003765:Models, Dental; D015588:Observer Variation; D011856:Radiographic Image Enhancement / Q000592:standards*; D016300:Radiography, Bitewing / Q000592:standards* / Q000706:statistics & numerical data; D014962:X-Ray Film / Q000592:standards / Q000706:statistics & numerical data